One of the oldest known workplace dangers is breathing in tiny bits of silica, which is essentially sand. Even the ancient Greeks knew that stone cutters got sick from breathing in dust. And today, nearly two million American workers are exposed to silica dust in jobs ranging from construction to manufacturing. A safety agency at the Department of Labor wants to put much stricter controls on silica exposure, but as NPR's Nell Greenfieldboyce reports, the proposed new rules have been stuck in a kind of regulatory limbo. This is today's bottom line in business.

NELL GREENFIELDBOYCE, BYLINE: The Department of Labor has been trying to prevent silica-related lung diseases for a long time.

(SOUNDBITE OF MOVIE, "STOP SILICOSIS")

UNIDENTIFIED MAN: 1935: A wave of fear was sweeping the country.

GREENFIELDBOYCE: Over 70 years ago, the department produced this movie, called "Stop Silicosis."

(SOUNDBITE OF MOVIE, "STOP SILICOSIS")

UNIDENTIFIED MAN: Cause of the disease: dust. Results of the disease: disablement, poverty, death. Cure for the disease: none.

GREENFIELDBOYCE: People with silicosis can have a cough, shortness of breath and go on to develop serious infections and respiratory failure. Silica can also cause other diseases, like lung cancer. The current limit on how much silica workers can inhale was set decades ago. Workplace safety experts say that exposure limit needs to be lowered so that it's half what it is today.

And on Valentine's Day back in 2011, it looked like a safety agency at the Department of Labor was getting ready to do that. It sent a proposed new silica rules to a White House office for a routine review that was supposed to take 90 days. Almost two years later, those rules are still under review.

GREENFIELDBOYCE: Peg Seminario is director of safety and health for the AFL-CIO, a group of 57 unions that represents more than 12 million workers. She says their push for a new silica rule goes way back.

SEMINARIO: We had hoped back under the Bush administration it would move, and it didn't. And then we certainly hoped under the Obama administration that a silica standard would move forward. And unfortunately, it's been stuck over at OMB and the White House now for two years.

GREENFIELDBOYCE: She says the government's own estimates show the impact of waiting.

SEMINARIO: Every year this rule is delayed, another 60 workers will die. That's deaths. That's not to even look at the numbers of workers who will become sick. We still have thousands of new cases of silicosis every year in this country.

GREENFIELDBOYCE: Tom Ward knows just how bad silicosis is. He's a mason who lives and works in Michigan. He says when he was a kid, his dad developed silicosis after working as a sandblaster.

TOM WARD: The last day he worked, he came in and fell down and, you know, pretty much, you know, fell apart, basically, and said I can't do it no more.

GREENFIELDBOYCE: Ward says his father got the official diagnosis at age 34, and died at age 39.

WARD: So we watched him slowly suffocate for five years.

GREENFIELDBOYCE: When Ward grew up and started working as a bricklayer and a mason, he had no idea that the saws and grinders he used were spewing out dust that could expose him to silica, until he finally took a safety course.

WARD: From that point on, my view on how we cut things at work changed dramatically, to say the least.

GREENFIELDBOYCE: He's now 44, and wonders if he'll develop lung disease. He also worries about the apprentices he teaches at a union training center who are about to start their careers in construction.

WARD: They're not going to go complain about anything right now, especially with the economic conditions. Everybody is really scared for their job, and they're not going to say a thing about safety.

GREENFIELDBOYCE: That's why he wants to see the government take action on silica, to release the proposed rules so they can be publicly debated, and then, hopefully, finalized. Last year, he went with other worker advocates to talk with officials at the White House Office of Management and Budget.

Now, there are also lots of people who don't want to see the silica exposure limits cut in half, and they've been making their case to officials at OMB, too. Opponents to the new rule include a slew of trade associations for the makers of brick, steel, concrete, producers of sand, stone and gravel, as well as road builders and general contractors. Amanda Wood is director of labor and employment policy at the National Association of Manufacturers.

AMANDA WOOD: The rule would cost manufacturers - and the industry as a whole - billions of dollars a year. That is just not sustainable for manufacturing when employers are looking to hire and create new opportunities for job creation.

GREENFIELDBOYCE: She says besides the economic cost, consider that silicosis deaths have already dropped more over 90 percent, compared to decades ago.

WOOD: So based on these two factors, we do not believe that the rule is necessary.

GREENFIELDBOYCE: Others say instead of issuing a new silica rule, the government should better enforce the existing one. Brian Turmail is a spokesperson for the Associated General Contractors of America. He says inspections show that many employers don't obey the existing law.

BRIAN TURMAIL: They're finding that firms aren't complying with the current limit about a third of a time. We're going to get a lot more improvement in workplace safety if we just can work together to make it so that everyone can comply with the current standard than we're ever going to get out of changing the standard to a new and even more unattainable level.

GREENFIELDBOYCE: The safety agency at the Department of Labor that is trying to get this new rule out is OSHA, the Occupational Safety and Health Administration. And the guy who heads OSHA is an epidemiologist named David Michaels. He doesn't buy the industry arguments. For example, take this issue of enforcement.

DAVID MICHAELS: Even if 100 percent of employers kept exposures at the current standard, silica-exposed workers would still be at increased risk for lung cancer, silicosis and chronic obstructive lung disease.

GREENFIELDBOYCE: And he says, OK, silicosis deaths have dropped.

MICHAELS: Exposures have gone down from the terrible exposures that occurred, you know, the years before OSHA, or in the very first years, but still there are plenty of people exposed to dangerous levels, and we can't ignore that.

GREENFIELDBOYCE: He says OSHA is required to do extensive studies to show that every industry can comply with the proposed rules without hurting their bottom lines or hurting jobs.

MICHAELS: There will be people who will say that our proposal will hurt employment in the United States, and that's simply not true. We've looked at the industry analyses, and they're wrong.

GREENFIELDBOYCE: Michaels is well aware that some worker advocates are frustrated that the White House review has gone on for almost two years.

MICHAELS: Look, I sympathize with those advocates. The process that the law requires us to go through is a very long and complicated one.

GREENFIELDBOYCE: But he says they've completed their analyses and expects the proposed rules to be made public this spring. A spokesperson for the White House Office of Management and Budget said it does not comment on rules under review. Nell Greenfieldboyce, NPR News.

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